Chemical composition of crushed stone and gravel. Specifications and types of crushed stone. The difference between crushed stone and gravel

Crushed stone is called loose solid material, consisting of fragmented rocks, stones, coarse gravel, or waste from the activities of enterprises for the processing of ore and other minerals. In terms of popularity, crushed stone is not inferior to gravel. Outwardly, it looks like it, but its particle structure is different. Gravel pebbles look run-in and rounded, while crushed stone has sharp contours and a rough surface. Although their composition may not differ from each other.

The main difference between these materials is their origin. Crushed stone is obtained artificially by crushing rocks, while gravel is formed during natural processes. As a rule, this takes a long time. The rate of formation of crushed stone is incomparably higher and is determined by the strength of the rock and the power of the mechanisms for crushing it. It can be said that gravel has a historical past, while rubble has practically none.

Sharp angular edges, the presence of numerous protrusions also distinguish crushed stone from gravel. Such properties of it provide better adhesion to the cement mass than river gravel, which makes it more preferable in construction. But its decorative qualities are lower.

The composition of crushed stone may be the same as that of gravel, or it may differ. It all depends on what material the rubble was obtained from. If it is a natural rock, then the composition will be similar (i.e., natural). However, crushed stone can also be produced from industrial and construction solid waste: ceramics, slag, etc. Mineral composition crushed stone obtained from their rocks, depends entirely on their composition. It can be obtained from rocks of igneous origin (granite, basalt, etc.), metamorphic (marble, gneiss, etc.), sedimentary (dolomite, limestone).

According to the size of the fractions, crushed stone is divided into several types. The most commonly used so-called standard classification, which includes 7 size intervals:

1. 0.3 - 0.8 cm;
2. 0.5 - 1 cm;
3. 1 - 2 cm;
4. 2 - 4 cm;
5. 2.5 - 6 cm;
6. 2 - 7 cm;
7. 4 - 7 cm.

Crushed stone of the smallest fractions is called eurocrushed stone.

The density of the material is, on average, 1.2 - 3 g/cm3.

The strength of crushed stone is entirely determined by the strength of the material from which it was obtained. For road construction, crushability and wear resistance are important.

In terms of strength, crushed stone can be of high strength, high strength, medium strength, low strength and very low strength. The number of rock particles with low strength is taken into account when normalizing. Most best brands strength: M1200, M1400, M1000. Material with the brand M1400 - 1600 is used less frequently, mainly to create durable concrete for capital structures.

flakiness

Determines the degree of flattening and elongation of components. The higher it is, the lower its quality. On this basis, crushed stone of the cuboid, improved, ordinary and flaky types is distinguished. The use of lamellar and needle-shaped gravel leads to the appearance of microvoids in concrete mix. The use of such a material requires a large amount of cement per unit mass of concrete.

The only area where the use of crushed stone with increased flakiness is appropriate is the construction of roads and railways. This is due to its better ability to pass water through itself.

Frost resistance

Determined by the number of freeze-thaw cycles. According to this indicator, there are brands from F15 to F400. The number after F indicates the number of cycles. For construction, grades F300 and above are suitable.

Radioactive properties

They define the scope of this material. The level of radioactivity must be confirmed by certificates and other documents. Granite crushed stone may have a higher radiation background than its other varieties. Increased radioactivity is allowed during the construction of roads at a distance from settlements, although this is not entirely correct, given the possibility of future development in uninhabited areas.

Crushed stone can be gravel, limestone, granite, slag, secondary.

Gravel crushed stone is obtained by crushing rocks in a quarry, as well as from rocky rocks. Crushed gravel differs from granite in that it is less durable, but environmentally it is considered safer, since it rarely has elevated level radiation.

Such crushed stone is used in the production of concrete, in road construction, for the production of reinforced concrete products, when laying dirt roads and paths for pedestrians. Concrete on crushed gravel is less durable than on granite, but at the same time more durable than on artificial crushed stone. building materials.

According to the particle size, crushed gravel is divided into small (3-10 mm), medium (5-20 mm), large (0.5-4 cm) and very large (2-4 cm). Standardized according to GOST 8267-93.

Gravel crushed stone is obtained in much the same way as its other types. First, pieces of rock are placed with a loader into a special bunker, after which the crusher separates these rocks into small pieces. Next, the resulting material is divided into fractions.

For the price, this material is relatively inexpensive. It is cheaper than crushed granite. When it is obtained, it also requires less energy than when obtaining crushed granite.

Sometimes gravel is also classified as gravel rubble.

Limestone crushed stone is the result of crushing limestone, which mainly consists of calcium carbonate. It is used in the construction of roads, the production of reinforced concrete. Can be used for drainage purposes (some types).

Granite crushed stone is obtained by crushing hard granite rocks, which usually have a granular structure. The composition of granite includes: quartz, feldspar, mica, etc. The material has a pink, red or grayish color, which depends on the ratio of the main components. Granite crushed stone has the highest specific gravity.

Since granite rock is very hard, explosions are used to crush it. Further crushing is carried out in a special device, and then the resulting material is distributed according to the prevailing sizes.

The smallest fraction is used as decorative material, for sprinkling roads, when arranging recreation areas, when receiving concrete.

Medium fractions are used in the manufacture of concrete, including for foundations, in the construction of bridges, for pouring roads, runways at airfields, in the production of reinforced concrete, industrial buildings etc.

Large fractions also go to the production of concrete, and are also in demand in the construction of massive facilities, railways.

The largest fraction can be used in the construction of fences, pools, artificial ponds and as a decorative stone.

Granite crushed stone is one of the most durable materials, with high frost resistance and low level flakiness (elongation, flattening of components). Granite is considered an excellent aggregate for concrete, giving it high strength.

Secondary crushed stone is obtained by crushing construction waste, such as asphalt, concrete, brick. This material is considered the cheapest type of crushed stone. When received, it is spent minimal amount energy (up to 8 times less). The cost of concrete produced using this material.

Secondary crushed stone has low strength and resistance to frost. Nevertheless, it is actively used as an aggregate for concrete, for laying dirt roads, as a tamping material, and also to increase soil stability.

Slag crushed stone is produced from the waste of metallurgical industries. Such material is cheaper. The bulk density is 1000 kg per cubic meter. Some slag rubble has a porous structure. They are made from melts high content gases. The density of such material is from 400 to 1600 kg in one cubic meter. Bulk density is 800 kg/m3 and less, and therefore is used to obtain lightweight concrete.

In addition to being included in the composition of concrete, this material has also found application in the construction of roads and in order to strengthen soils under construction.

Produced from natural stone igneous effusive rocks - porphyrites of a homogeneous massive deposit in Karelia and Ukraine.

№	Indicators	indicator value
1.	stone density	2.75-2.93 t/m3
2.	Water absorption	0,05-0,25%
3.	Compressive strength	Until 2080/cm2
4.	Porosity	0,40-4,03%
5	Chemical composition:
	SiO2	48-65%
	Al2O3	15-18%
	CaO	3.5-10.5%
	MgO	2.1-7.2%
	SO3	0.38-1.01%
	Fe2O3	7.0-12.5%
6.	Total specific efficiency of natural radionuclides	30-137 Bq/kg which corresponds to class 1
7.	Bulk bulk density of crushed stone by fractions:
	from 0 to 5 mm.	1.50 t/m3
	from 0 to 40 mm.	1.53 t/m3
	from 3 to 10 mm.	1.45 t/m3
	from 5 to 20 mm.	1.37 t/m3
	from 20 to 40 mm.	1.41 t/m3
	from 20 to 60mm.	1.45 t/m3
	from 20 to 90 mm.	1.48 t/m3
	from 40 to 70 mm.	1.47 t/m3
	rubble stone	1.60 t/m3
8.	Frost resistance	F-300 (GOST from F 15 to F 400)
9.	Strength brand of crushed stone	1400 (GOST from 600 to 1400)
10.	Wear grade of crushed stone	I-1 (GOST from I-1 to I-4)
11.	Content of weak grains	0.1-3% (GOST up to 5%)
12.	The content of dusty, clay particles, including clay in lumps	Up to 1% GOST 1% Not more than 0.25% GOST 0.25%
13.	Grain content of lamellar shape	12-30% GOST up to 35%
14.	Grain composition	Complies with GOST 8267-93
15.	The content of harmful components	Missing

According to the results of gamma spectrometric studies, the specific effective activity of natural radionuclides in samples of building materials was 30-137 Ek / kg, which corresponds to the 1st class of building materials in terms of the content of natural radionuclides.

The useful thickness of the deposit is represented by volcanic rocks of predominantly medium and basic compositions, there are differences of acidic composition.
Porphyry and microporphyry, predominantly of dacitic composition - 36%. Porphyries and microporphyrites of andesite, basalt and transitional compositions - 57%.
Porphyrites are the most widespread in the deposit, and among them are porphyrites of andesite-basalt (20%) and basalt (16%) composition. Less common are andesitic porphyrites (13%) and dacitic-andesite porphyrites (8%).
Among the felsic varieties, porphyries of dacitic composition predominate (22%); liparitic-dacitic and trachytic varieties (7% each) occur.
Filsites, microgranites and diabases make up about 5%.
Clastolaves, lavoclastites, tuffs, tuff lavas are found in limited quantities - 2%.

1. Plagioclase, pyroxene - plagioclase porphyrites, microporphyrites of andesigotovo, andesite-basalt and basalt compositions.

Tonsils make up 10-15% of the rock volume and are filled with fine-grained quartz aggregate, chlorite, and epidote.

2. Plagioquasial porphyrites and microporphyrites of andesite-dacitic composition.

• Plagioclase - 58%
• Quartz - 10%
• Chlorite - 14-16%
• Carbonate - 10-12%
• Sericite - 7%

Porphyrite segregations make up about 10% of the rock volume and are represented by plagioclase. Plagioclase is sometimes replaced by carbonate chloride aggregates. Rutile is noted as ore materials.

3. Porphyrites and microporphyrites of quartz, quartz-plagioclase of liparite-dacitic, dacitic compositions and felsite.

• Albit - 31-51%
• Quartz - 25-35%
• Chlorite - 10-12%
• Carbonate - 5-14%
• Epidote - 1%
• Sericite - 2-13%
• Ore minerals 1-2% (leucoxene, rutile, magnetite, occasionally sulfides).

4. Microgranite

• Plagioclase (albite) - 57%
• Quartz - 17-20%
• Chlorite - 25%
• Epidote - 1%
• Sphene-leucoxene - 1%

As a result of chemical analysis of monolithic effusives, the following contents of basic oxides (%) were obtained:

• SiO2 - 48.44 to 65.28
• Al2O3 - 15.6 to 18.07
• Fl2O3 - 7.02 to 12.56
• CaO3 - 3.50 to 10.52
• MdO - 2.10 to 7.26
• SO3 - 0.38 to 1.01

crushed stone strength characterize the tensile strength of the original rock during crushing (crushing) in the cylinder, and wear in the shelf drum. These indicators simulate the resistance of stone material when exposed to passing on the road. Vehicle and mechanical influences during the construction of road structures (laying and compaction with rollers).

Rubble enrich according to the principle of selective fragmentation. crushed stone takes place in a certain way. Stones of different strength are passed through it and as a result, the crushed product is obtained different sizes. Smaller will be crushed stone from stones of lower strength. With the help of fractionation, it can be screened out, and a homogeneous and durable product can be obtained.

Depending on the brand, crushed stone is divided into groups:

High strength - М1200-1400,
- durable - M800-1200,
- medium strength - M600-800,
- weak strength - M300-600,

Frost resistance crushed stone is characterized by the number of cycles of freezing and thawing. It is allowed to evaluate the frost resistance of crushed stone by the number of saturation cycles in a solution of sodium sulfate and drying. According to frost resistance, crushed stone is divided into grades.

AT rubble normalize the content of lamellar grains ( flakiness- from the word "bream", i.e. flat like a bream) and needle-shaped. Grains of lamellar and acicular shapes include such grains, the thickness or width of which is three times or more less than the length. According to the shape of the grains, crushed stone is divided into four groups (the content of grains of lamellar and acicular shapes,% by weight):
- I group up to 15%,
- II group from 15% to 25%,
- III group from 25% to 35%,
- IV group from 35% to 50%.

Adhesion One of the specific characteristics of crushed stone is adhesion. This parameter reflects the assessment of the quality of adhesion of bituminous binders to the surface of crushed stone. It should be noted that the color of crushed stone affects the quality of adhesion. Top performance on adhesion gives gray and dark gray crushed stone.

Water absorption and water saturation- this is the property of crushed stone to lose moisture in its pores. Moisture yield of crushed stone characterized by the amount of water in % (by mass or volume) lost by a standard material sample per day at a relative humidity of 60% of the ambient air and a temperature environment 20 degrees S.

Water permeability of crushed stone - This is the ability of crushed stone to pass water under pressure. Water permeability is characterized by the amount of water that has passed within 1 hour through a sample of 1 meter in area and 1 meter thick at equal pressure.

Grain composition of each crushed stone fraction must meet the requirements of GOST 8267-93 “Crushed stone and gravel from dense rocks for construction works". Based on the requirements of the specified GOST, it follows that in the crushed stone fraction supplied for construction, for example, 20-40 mm, the amount grain size finer than 20 mm should not exceed 10%, and grains larger than 1.25 * D (50 mm) - no more than 0.5%.

Radioactivity- an important characteristic of crushed stone. Note that the radioactivity of natural crushed stone from natural granite rocks is always higher than that of limestone or gravel crushed stone. This is due to the nature of the occurrence of rocks.

Reactivity rubble from 51 to 261 mol/l.
Materials were selected according to geological reports of 1951, 1980, 1988.

Crushed stone, its varieties and features.

Crushed stone is one of the inorganic natural materials obtained by crushing rocks or as waste from enterprises for the extraction and processing of mountain ore. it bulk material with fractions of at least 3-5 millimeters in size, depending on accepted standards. In accordance with the density, shape and size of the fractions, crushed stone has different sphere applications.

Primarily, crushed stone is used in construction for the production of concrete in laying the foundation of buildings and production reinforced concrete structures. In addition, crushed stone is used during the construction of roads and bridges. Also, this material serves as a ballast layer of the railway track. In landscape design, crushed stone plays a role decorative coating all kinds of paths and platforms.

Among the varieties of rubble the hardest is crushed granite. It is obtained by crushing granite rock, which is a magma frozen at a depth. Such crushed stone can have a gray, red or pink tint, and its composition is based on feldspar and mica. Granite crushed stone is the most durable and frost-resistant in comparison with other types. Usually, to produce this material, a monolithic granite rock is blown up, and the resulting blocks are crushed in a special machine.

More affordable considered gravel. This variety is obtained by crushing stone rock or sifting quarry rocks. This crushed stone is inferior to granite in terms of strength and other characteristics, but it has a low radioactive background. The properties of crushed gravel make it possible to use it in the construction of road surfaces and in the production of reinforced concrete structures. In turn, this category is divided into crushed stone and gravel.

Another variety is limestone rubble, also known as crushed dolomite. It is obtained as a result of crushing limestone - a sedimentary mountain of rock, the basis of which is calcium carbonate. Unlike the previous types, crushed limestone undergoes a special chemical treatment. The strength of this material is not so high, but it is enough for the production of small concrete products. Limestone crushed stone is also used in the glass and printing industries.

It should be noted that crushed stone quality is determined not only its strength. It has a number of other characteristics, in particular, flakiness. This parameter determines the planar features of the given material. In addition, frost resistance of this building material plays a significant role in determining the quality of crushed stone. It is determined by the number of freeze and thaw cycles, which is characterized by the corresponding brand.

Crushed stone is one of the main materials in various construction industries. This non-metallic loose material is mined by explosive method in quarries. Next, the stone is crushed into the appropriate fractions.

The main types of crushed stone

• gravel crushed stone. Reliable material with a low radiation background, capable of withstanding up to 200 freeze / thaw cycles without loss operational properties. It is obtained from loose rock. The main characteristic is the strength grade.

Gravel gravel is used as a filler in the creation of concrete solutions and reinforced concrete products, as well as in the construction of platforms and paths, as a ballast layer for the construction of railway tracks, etc. The main fractions are 40-70 mm, 3-10 mm, 20-40 mm, 5-20 mm.

• Limestone (dolomite) crushed stone belong to the group of the most common materials. Its undeniable advantage is ecological cleanliness. At a cost, it is slightly inferior to rubble stone; you can order it on the website. The disadvantages of dolomite crushed stone include low strength. Produced by crushing sedimentary rocks consisting of calcite, after which it passes chemical treatment. The material is presented in yellow, gray, white, brown and red.

The scope of the material is the construction of buildings and roads with a low load. It is also used as a filler in commercial mixtures, in the drinking, glass and printing industries, in the preparation of Portland cement.

• Granite crushed stone. The most demanded material in modern construction. Such high popularity is explained by low water absorption, high frost resistance and resistance to abrasion. It is mined from sedimentary rocky and loose rocks with subsequent crushing.

The main fractions of crushed granite are recognized

The standards for this type of material are prescribed in GOST 8267-93. Asphalt and concrete are produced on the basis of crushed stone with a fraction of 5-20 mm. Also, this material acts as a filler for reinforced concrete and concrete (bridge and monolithic structures, critical concrete), participates in the construction of bases and road surfaces, plays the role of a ballast layer for railway tracks, etc.

• Secondary crushed stone. This type of building material is used in backfilling of highways and exits to construction sites. Used secondary crushed stone as a filler concrete mortar, as well as in the construction of the lower layers of federal highways.

• Slag crushed stone. Gets it by crushing metallurgical blast-furnace slag. The material is characterized by low flakiness and dust resistance, has an average frost resistance and strength. low bulk density crushed slag in combination with affordable cost allows its use in the manufacture of ready-mixed concrete (fraction 5-20 mm) and road construction (fraction 20-40 mm and 40-70 mm).
• decorative gravel. Used in the design of fountains, flower beds, " alpine slides". This material is available in yellow, white and red.

The main characteristics of crushed stone

The scope and properties of the material are determined by its characteristics. Let's consider them in more detail:

• Adhesion- the ability of the material to bind to substances;
• flakiness. It characterizes the flatness of crushed stone - the ratio of length to thickness. AT high quality material the number of lamellar or needle-shaped particles should be minimal;

• Strength. Allows you to determine the resistance to abrasion, compression, crushability. It is marked with the letter "M" and a number. The higher the indicator, the stronger the crushed stone;
• Frost resistance- the ability of crushed stone to withstand numerous freeze-thaw cycles without loss of quality. Indicated with the letter "F" and a number (from 15 to 400). The most demanded in construction is crushed stone F 300.

Before you buy crushed stone, you should familiarize yourself with its types and determine the most suitable one for your project. Experts recommend checking the availability of a quality certificate for products.

Depending on the type of crushed stone has certain technical characteristics. When choosing the type of crushed stone, it is necessary to take into account not only its fractionation, but also its characteristics.

In accordance with GOST, the following main characteristics of crushed stone are distinguished:

Frost resistance. This property shows the ability of crushed stone to withstand alternate freezing and thawing in a wet state while maintaining properties and structure. According to frost resistance, types of crushed stone are: highly resistant (F200,300,400), stable (F50,100,150) and unstable (F15.25).

Strength characterizes the ability of crushed stone to withstand loads of a certain magnitude. By strength, crushed stone is distinguished: heavy-duty (M1400-M1600), high-strength (M1200-1400), strong (M800-M1200), medium strength (M600-M800), low strength (M300-M600), very weak strength (M200).

Flakiness. This is the main and very important property of crushed stone, showing the presence of relatively even edges (sides) on the "grains" in the total mass of crushed stone. By flakiness, crushed stone is: cuboid - 1 group, improved - 2 group, ordinary - 3 group. The most effective is crushed stone of the 1st group of flakiness. It is easy to rammer, more durable. Cuboid crushed stone is an excellent material for creating foundations and paving.

Types of crushed stone by origin

Depending on which rock the material was made from, the following types of building rubble are distinguished:

• granite;
• gravel;
• limestone (dolomite);
• slag;
• slate;
• secondary.

Granite crushed stone produced on the basis of a granite mountain range. As a rule, this type of crushed stone has a reddish color and uneven edges. However, this only improves the ability to adhere to cement mortar in the concrete mixture, which provides good strength characteristics.

Currently, several types of crushed granite are produced, depending on the fraction. The size of "grinding" crushed stone from granite can vary from 0-5 mm to 70-120 mm. Granite crushed stone is a widely demanded building material due to its excellent technical characteristics. Depending on the fractional composition, crushed granite is used in various fields.

Gravel crushed stone is obtained by screening quarry rocks, or by an explosive method in the development of stone rocks. Crushed stone is a grayish mass of various fractional composition. For the production of crushed stone, they are guided by GOST 8267-93, where the required technical characteristics of the material and production technology are prescribed. Compared to granite, crushed gravel has less strength, which predetermines the scope of its application.

The largest brand in terms of strength of crushed gravel is only M 1200. Although gravel crushed stone is inferior to granite in such characteristics as strength and appearance, it has quite a number of advantages. The process of extracting crushed gravel is much easier than granite and requires less effort and money. The fact is that rocks are less durable than granite ones, which means that less powerful equipment and machines will be required for their development. In addition, gravel is considered a very common material, which also leads to a relatively low cost of the material.

The prevalence of “deposits” of crushed gravel contributes to great competition in the extraction of this material, which also reduces its market value. Gravel rubble has a lower radioactive background than granite. Gravel crushed stone is produced in four fractions: 3-10 mm, 5-20 mm, 5-40 mm, 20-40 mm.

Limestone (dolomite) crushed stone, as a rule, is used in construction in lightly loaded structures. It can be used for the production of piece products from reinforced concrete, provided that these parts will not be heavily loaded. Lime crushed stone is a product of crushing sedimentary rocks, consisting mainly of calcium carbonate. Limestone crushed stone is mined in quarries. The material is quite widespread, so crushed limestone is quite inexpensive.

Limestone crushed stone has little strength, so its scope is much narrower than that of granite or gravel. Crushed stone is widely used in road construction when laying a roadbed with a low load. Also, crushed limestone is widely used in the production of lime, soda and mineral fertilizers. Lime crushed stone is produced in three types of fractions, which determine the scope of their application. Crushed limestone is produced in fractions of 5-20 mm, 20-40 mm and 40-70 mm.

Slag crushed stone is an affordable building material obtained from the waste of metallurgical and chemical industry, as well as when burning solid fuels. Slag crushed stone has a high density. Its density is higher than that of crushed granite. However, high density characterizes a large mass of material, which in construction is a fairly significant drawback. Slag crushed stone has a higher water absorption coefficient compared to granite. Therefore, structures erected with such rubble should not often come into contact with moisture.

Slag crushed stone should also not be subjected to frequent freezing, because the frost resistance characteristics of this material are very small (only 15 cycles against 300 cycles of granite crushed stone). The use of crushed slag is advisable in the case of a full account of all its shortcomings. In general, depending on the fraction (0-5, 5-20, 20-40, 40-70, 70-120 mm), crushed slag is quite often used in civil and road construction, as well as in the production of building materials.

Shale crushed stone is a material obtained from rocks of volcanic origin. Externally, slate rubble will look like an oblong, flat mound of stone. The color of slate gravel can be burgundy, yellow, brown, gray, anthracite or green. Shales are widely used in construction and production of materials. For example, there is a rock of slates, when splitting which, many of the thinnest plates are formed. Such slates are used for roofing materials.

The product of shale crushing is crushed stone, which is also widely used in construction. Shale crushed stone is used for the construction of roads and monolithic reinforced concrete structures, as well as for decorating the landscape. Depending on the faction, decorative elements of the adjacent territory are decorated with slate gravel, creating interesting paths. However, it should be borne in mind that before choosing a specific fraction and type of slate rubble, it is necessary to study its characteristics in detail.

Currently, the so-called secondary crushed stone is quite common. It is obtained by crushing construction debris. Produce secondary crushed stone by crushing monolithic structures, having previously removed the reinforcing frame and metal embedded parts from them during the primary split.

Secondary crushed stone, due to its relatively low cost, has a very cheap price. So, for example, when compared with granite, secondary crushed stone from construction waste will cost about half as much. Reducing the cost of concrete, obtained on the basis of secondary crushed stone, will be up to 30%, compared with mixtures on granite aggregate. However, such a low cost of the material also indicates its reduced strength and frost resistance. The maximum grades for strength and frost resistance of secondary crushed stone are M800 and F150, respectively. However, even with such indicators, secondary crushed stone can be used in various fields.

On the site portal you can study information on the types of crushed stone with the presented color photos of materials, as well as find out where at the lowest price.

Types of gravel and granite crushed stone by fractional composition

Speaking about what types of crushed stone are, do not forget about its fractional division. Depending on the feedstock, one or another crushed stone is produced in several types of fractions. The most common in the construction of granite and gravel crushed stone.

Gravel crushed stone of a fraction of 3-10 mm goes to screenings, 5-20 mm is used in the production of small-sized building products (paving slabs etc.), 20-40 mm - for larger monolithic products (for example, rings for a well). Crushed stone from gravel with a fraction of 20-40 mm is widely used for the production various concretes and reinforced concrete structures.

Granite crushed stone has a more diverse fractionation. Depending on the type of crushed granite fraction, its application also depends. So, for example, a fraction of crushed granite 5-20 mm is considered fine and is widely used for monolithic construction.

Crushed stone of medium fraction 20-40 mm is also excellent for concrete and the production of reinforced concrete structures. A coarse fraction of 20-40 and 40-70 mm is appropriate when it is necessary to produce large volumes of concrete, as well as for pouring large, massive structures. Such rubble is suitable for the construction industrial facilities and highways. Fractions of crushed granite 70-120, 120-150, 150-300 can still be called rubble. Such crushed stone, as a rule, is used in more decorative purposes. For example, to build stone fences and hedges. The smallest fraction of crushed granite 0-5, 0-20, 0-40 mm is widely used in road construction.

Scope of application

The types of rubble are very diverse. However, the use of crushed stone in construction is extremely common and in demand. Currently, the use of crushed stone in the construction of buildings, structures and roads affects almost all stages of construction. Thanks to high-quality crushed stone, strong, durable structures are obtained that ensure the safety of buildings and structures under construction.

However, crushed stone is also widely used in applications such as landscape design. Small fractions can be safely used for filling in flower beds, creating alpine slides, and large fractions for laying paths or stone fences.

It will help you understand the variety of rubble, as well as pick up necessary materials at low price.

Crushed stone has a loose structure, consisting of uncut pebbles. It is obtained by crushing granite, gravel and boulders. Its formation occurs by natural destruction of rocks, but in construction, material obtained by artificial means is used.

Crushed stone has a loose structure, which consists of small stones.

Crushed stone, the technical characteristics of which are adhesion and fraction, is one of the most common building materials. Also different kinds crushed stone have their own characteristics, such as:

• radioactivity;
• strength;
• frost resistance;
• interaction with a humid environment.

Fractions, characteristics of crushed stone

Crushed stone is divided into fractions, that is, according to the size of the grains. There are two types:

• basic;
• accompanying.

The main fractions come in the following sizes: 5-10 mm, 5-20 mm, 20-40 mm, 20-65 mm, 25-65 mm, 40-70 mm. And the accompanying ones have a small section: from 0-2 mm to 0-60 mm and 2-5 mm. But there is crushed stone with a larger fraction from 70 to 120 mm.

grain composition. These characteristic data determine the material homogeneity structure. With the most homogeneous structure, the density and shrinkage of crushed stone significantly increase. So, compliance with the construction technology depends on foreign impurities, the less clay, dust and foreign additives in the composition, the greater the adhesion of the material.

The presence of foreign matter. The presence of clay and dust-like elements in crushed stone is provided taking into account the norms, the permissible diameter of which is at least 0.5 mm. In addition to dust, it is necessary to highlight the presence of clay lumps, the particle size is 1.25 mm, and it should not be larger than the granules of the gravel fraction. The presence of all clay and dust-like particles is not allowed higher than 0.25% of the total mass. This applies to any brand. In material from igneous rocks, the maximum allowable presence of impurities is not more than 1%, and from sedimentary rocks, a maximum of 2%.

Frost resistance. Specifications material are determined by the number of cycles of freezing and thawing of fractions without destruction. It is possible to determine frost resistance by the saturation of sodium sulfate in the composition and its drying. Gravel is also divided into brands according to its frost resistance.

Flakiness. The advantages of the material are evaluated by one of the important parameters - flakiness, which means the presence of lamellar and needle-shaped forms. Such granules include grains whose width parameters are three times less than their length. By their appearance, the granules are divided into subgroups, which contain lamellar and needle-shaped grains:

• cuboid;
• improved;
• ordinary.

Scheme of crushed stone varieties: a - cuboid, b - acute-angled, c - wedge-shaped, d - flaky.

It should be taken into account that the lower the flakiness, the higher the preferential parameters. Of all types, cube-shaped gravel is considered the most practical, as it provides a very dense compaction. If lamellar and acicular granules are present in the gravel, this entails an increase in voids in the composition. This leads to an increase in binder components, and in connection with this, cash costs increase. From this follows the conclusion that it is advisable to use a cubic material from the point of view of economics.

Strength. The strength of the finished gravel depends on the tensile strength of the rock itself, which is tested by compression or crushing in a cylinder. Based on the definition of strength, it is divided into groups:

• high-strength from M1200 to M1400;
• durable from M800 to 1200;
• medium strength from M600 to M800;
• low strength from M300 to M600;
• very weak strength from M300 to M200.

The presence of small granules and medium grains in crushed stone, it is not allowed to exceed the established norms. The test is carried out by standard compression with the required water saturation up to 20 MPa. Gravel M1000, M1200, M1400, based on the GOST 8267-93 standard, the presence of weak rocks in such materials should not exceed 5%, and crushed stone M400, M600, M800 should not contain more than 10%, M300 and M200 - 15% of the total masses.

Granite crushed stone of the M1200 brand is very popular. But the high-strength material of the brand M1400 - M1600 is used very rarely. It found its application in the manufacture of high-strength concrete, foundations and structural elements for bridges.